1. Field of the Invention
The present invention to electronic sign displays and, more particularly relates to pixel interleaving configurations for use in high definition electronic sign displays.
2. Description of the Prior Art
Prior art electronic sign displays have often incorporated a plurality of light emitting diodes (LEDs) as a prime emitter of light or points of light, whereby visual perception is processed by the eye of a viewer as a graphic presentation. Electronic sign displays have evolved from those having moderate resolution to those having an improved degree of resolution approaching or equaling high definition video, such as brought on by the advent of high definition (HD) television devices. There is a desire for high definition, i.e., high resolution, indoor or outdoor LED displays reflecting the current trend in the ever increasing quest for picture-like HD video quality. There are two primary standards for HD video, one is 720p and the other is 1080i. The 720p standard uses 720 progressively scanned lines of multiple pixel groups of full color red, green and blue (RGB) LEDs, where each RGB LED group constitutes a single pixel that collectively create a video image frame for accumulated perception as an image by the human eye. For example, a progressive scan could use 1/60th of a second for each frame. The other standard is the 1080i standard, that supports 1080 lines of resolution by interleaved scanning. In interleaved scanning, the odd lines are illuminated for 1/60th of a second followed by the even scan lines for 1/60th of a second, giving a full frame of data in 1/30th of a second. Each video standard is independent of the light emitting technology, and therefore can be supported by CRT (cathode ray tube), LCD (liquid crystal displays), plasma, or LEDs (light emitting diodes). Light emitting diode displays are often the preferred technology for large video displays because they are capable of creating a high contrast, bright display. Producing such high resolution light emitting displays requires the addition of LEDs where the quantity of LEDs are increased in great quantity to achieve desired clarity, resolution, definition and brightness. Because every pixel in those lines of resolution has a red, green, and blue component associated with it, every pixel should have a red, green, and blue LED to display all the video information available for that pixel clement. LEDs are a very significant percentage of the cost of an LED screen, and therefore, a screen with 720 pixels high by some arbitrary number of pixels wide can be extremely expensive and, therefore, cost prohibitive for many users. Such an increase in the number of LEDs required for high definition resolution use can be problematic in terms of LED cost and in terms of energy usage. Size limitations are also a cause of concern. There are two approaches with respect to LED structuring when building a high definition electronic sign display. One approach uses a plurality of individual LEDs where each LED is an individual colored red, green, and blue LED, thereby forming a pixel. The physical size of these lamps along with the requirement to have at least three LEDs (red, green, and blue) limits how tightly the spacing can be between full color pixel elements. Alternatively, these lamp-style LEDs can be inserted through the circuit board as part of an LED package directly affixed to the face of the circuit board. This second approach is a surface mount device (SMD) package that preferably includes red, green, and blue LEDs in one package. Combining all three color diodes into such a single SMD LED package allows for tighter pixel spacing and is limited only by the size of the SMD package itself. In addition to typical video format displays, there are many applications pertaining to vertically small but very long displays. Some examples of these applications include financial ticker displays, or programmable electronic advertising displays, such as Daktronics, Inc. ProAd® product often found in stadiums and arenas. These displays are often between 1-4 feet tall, but can be tens or even hundreds of feet long. Vertical pixel resolution has a significant impact on the image quality of these displays and is beneficial to advertisers who want a high quality image when they are paying to advertise their product/company through the use of such a device. Clearly what is desired is a solution addressing the shortcomings of prior art devices where such a solution is introduced by the present invention.